1. Field of the Invention
The invention relates to a needle assembly for use in drawing bodily fluids, such as blood. More particularly the needle assembly is designed so that the free ends of the needle are covered before use and may be covered after use in a manner which greatly reduces the risk of accidental puncture wounds.
2. Description of the Prior Art
Needle assemblies for drawing bodily fluids, in particular blood, are well known in the art. In general, these assemblies include a needle having a first end for puncturing the vein of a patient, and a second end for insertion into a evacuated, sealed empty container for receiving the patients blood. After a blood sample has been taken, the needle assembly is removed from the container now containing the blood and discarded.
As is well known, the epidemic of the Acquired Immuno Deficiency Syndrome (AIDS) has lead to concern that medical workers will be accidentally pricked by the needles after use. Accidents of this type are one documented means of becoming infected with AIDS. Therefore it has been considered of great importance in the art to avoid accidents, where doctors, nurses or other persons suffer puncture wounds from the use of needle assemblies. Presently, the safe disposal of used needle assemblies is considered a serious problem in the art. A recent article in the New England Journal of Medicine entitled "Rates of Needle-Stick Injury Caused by Various Devices in a University Hospital", published Aug. 4, 1988, highlights the fact that of the 326 injuries studied, 35 percent were caused by disposable syringes and 26 percent were caused by intravenous tubing and needle assemblies. Devices that required disassembly had rates of injuries of over 5 times the rate for disposable syringes In addition, one-third of the injuries were related to recapping. The article concluded that "Devices should be designed so that the workers hands remain behind the needle as it is covered, the needle should be covered before disassembly of the device and the needle should remain covered after disposal." Although this article documented the risk of needle-stick injuries, it did not propose any specific needle assembly designs for reducing such risk.
In order to prevent the occurrence of puncture wounds, where needle-stick injuries were accidentally self-inflicted by doctors or nurses, there has been some effort to provide simple methods for immediately covering the needle after use. U.S. Pat. No. 4,702,738 addresses this problem by disclosing a disposable hypodermic syringe with a retractable lockable sheath. Other patents, such as 4,356,822 also disclose a syringe assembly having a sheath that can be extended to cover the needle but which cannot be locked in the extended position. In addition, U.S. Pat. Nos. 4,237,882, 4,416,663, 4,573,972, 4,731,059, 4,139,009 and 3,967,621 also disclose syringe assemblies with various means for protecting the needle either before or after use. In addition, copending Application Serial No. 232,014 filed and owned by the inventor of the present invention also teaches a sheath assembly for protecting the exposed hypodermic needle.